#!/usr/bin/ksh
#
# iopending - Print a plot for the number of pending disk I/O events.
#             Written using DTrace (Solaris 10 3/05).
#
# This is measuring disk events that have made it past system caches.
# By plotting a distribution graph of the number of pending events, the
# "serialness" or "parallelness" of disk behaviour can be distinguished.
#
# $Id: iopending 3 2007-08-01 10:50:08Z brendan $
#
# USAGE:	iopending [-c] [-d device] [-f filename] 
#		          [-m mount_point] [interval [count]]
#
#		-c		# clear the screen
#		-d device	# instance name to snoop (eg, dad0)
#		-f filename	# full pathname of file to snoop
#		-m mount_point	# this FS only (will skip raw events)
#	eg,
#		iopending   	# default output, 5 second intervals
#		iopending 1  	# 1 second samples
#		iopending -c	# clear the screen
#		iopending 5 12	# print 12 x 5 second samples
# 	
# FIELDS:
#		value		number of pending events, 0 == idle
#		count		number of samples @ 1000 Hz
#		load		1 min load average
#		disk_r		total disk read Kbytes for sample
#		disk_w		total disk write Kbytes for sample
# 
# SEE ALSO: iosnoop, iotop
#
# IDEA: Dr Rex di Bona (Sydney, Australia)
#
# COPYRIGHT: Copyright (c) 2005, 2006 Brendan Gregg.
#
# CDDL HEADER START
#
#  The contents of this file are subject to the terms of the
#  Common Development and Distribution License, Version 1.0 only
#  (the "License").  You may not use this file except in compliance
#  with the License.
#
#  You can obtain a copy of the license at Docs/cddl1.txt
#  or http://www.opensolaris.org/os/licensing.
#  See the License for the specific language governing permissions
#  and limitations under the License.
#
# CDDL HEADER END
#
# Author: Brendan Gregg  [Sydney, Australia]
#
# 01-Nov-2005	Brendan Gregg	Created this.
# 20-Apr-2006	   "      "	Last update.
#


##############################
# --- Process Arguments ---
#

### default variables
opt_device=0; opt_file=0; opt_mount=0; opt_clear=0; 
opt_def=1; filter=0; device=.; filename=.; mount=.
interval=5; count=-1

### process options
while getopts cd:f:hm: name
do
	case $name in
	c)	opt_clear=1 ;;
	d)	opt_device=1; device=$OPTARG ;;
	f)	opt_file=1; filename=$OPTARG ;;
	m)	opt_mount=1; mount=$OPTARG ;;
	h|?)	cat <<-END >&2
		USAGE: iopending [-c] [-d device] [-f filename]
		                 [-m mount_point] [interval [count]]
 
		                -c              # clear the screen
		                -d device       # instance name to snoop 
		                -f filename     # snoop this file only
		                -m mount_point  # this FS only 
		   eg,
		        iopending         # default output, 5 second samples
		        iopending 1       # 1 second samples
		        iopending -m /    # snoop events on filesystem / only
		        iopending 5 12    # print 12 x 5 second samples
		END
		exit 1
	esac
done

shift $(( $OPTIND - 1 ))

### option logic
if [[ "$1" > 0 ]]; then
        interval=$1; shift
fi
if [[ "$1" > 0 ]]; then
        count=$1; shift
fi
if (( opt_device || opt_mount || opt_file )); then
	filter=1
fi
if (( opt_clear )); then
        clearstr=`clear`
else
        clearstr=.
fi



#################################
# --- Main Program, DTrace ---
#
/usr/sbin/dtrace -n '
 /*
  * Command line arguments
  */
 inline int OPT_def 	= '$opt_def';
 inline int OPT_clear 	= '$opt_clear';
 inline int OPT_device 	= '$opt_device';
 inline int OPT_mount 	= '$opt_mount';
 inline int OPT_file 	= '$opt_file';
 inline int INTERVAL 	= '$interval';
 inline int COUNTER 	= '$count';
 inline int FILTER 	= '$filter';
 inline string DEVICE 	= "'$device'";
 inline string FILENAME = "'$filename'";
 inline string MOUNT 	= "'$mount'";
 inline string CLEAR 	= "'$clearstr'";

 inline int MAX_PENDING = 32;	/* max pending value */
 
 #pragma D option quiet

 /*
  * Print header
  */
 dtrace:::BEGIN 
 {
        /* starting values */
        counts = COUNTER;
        secs = INTERVAL;
        disk_r = 0;
        disk_w = 0;
        pending = 0;

        printf("Tracing... Please wait.\n");
 }

 /*
  * Check event is being traced
  */
 io:genunix::start,
 io:genunix::done 
 { 
	/* default is to trace unless filtering, */
	this->ok = FILTER ? 0 : 1;

	/* check each filter, */
	(OPT_device == 1 && DEVICE == args[1]->dev_statname)? this->ok = 1 : 1;
	(OPT_file == 1 && FILENAME == args[2]->fi_pathname) ? this->ok = 1 : 1;
	(OPT_mount == 1 && MOUNT == args[2]->fi_mount)  ? this->ok = 1 : 1;
 }

 /*
  * Store entry details
  */
 io:genunix::start
 /this->ok/
 {
	/* track bytes */
	disk_r += args[0]->b_flags & B_READ ? args[0]->b_bcount : 0;
	disk_w += args[0]->b_flags & B_READ ? 0 : args[0]->b_bcount;

	/* increase event pending count */
	pending++;
 }

 /*
  * Process and Print completion
  */
 io:genunix::done
 /this->ok/
 {
	/* decrease event pending count */
	pending--;
 }

 /*
  * Prevent pending from underflowing
  * this can happen if this program is started during disk events.
  */
 io:genunix::done
 /pending < 0/
 {
	pending = 0;
 }

 /*
  * Timer
  */
 profile:::tick-1sec
 {
	secs--;
 }

 profile:::profile-1000hz
 {
	@out = lquantize(pending, 0, MAX_PENDING, 1);
 }

 /*
  * Print Report
  */
 profile:::tick-1sec
 /secs == 0/
 {
	/* fetch 1 min load average */
	this->load1a  = `hp_avenrun[0] / 65536;
	this->load1b  = ((`hp_avenrun[0] % 65536) * 100) / 65536;

	/* convert counters to Kbytes */
	disk_r /= 1024;
	disk_w /= 1024;

	/* print status */
	OPT_clear ? printf("%s", CLEAR) : 1;
	printf("%Y,  load: %d.%02d,  disk_r: %6d KB,  disk_w: %6d KB",
	    walltimestamp, this->load1a, this->load1b, disk_r, disk_w);

	/* print output */
	printa(@out);

	/* clear data */
	trunc(@out);
	disk_r = 0;
	disk_w = 0;
	secs = INTERVAL;
	counts--;
 }

 /*
  * End of program
  */
 profile:::tick-1sec
 /counts == 0/
 {
	exit(0);
 }

 /*
  * Cleanup for Ctrl-C
  */
 dtrace:::END
 {
	trunc(@out);
 }
'
